Have a 48 hr stop in NRT then either option from Oz should be fine - so long as you can change the ex Oz flights.
Many thanks! Good idea!
Actually, I just checked KrisFlyer and have snared SYD-SIN//overnight//SIN-LHR all on SQ A380 Suites for AUD90 and 148,000 pts. Substantial cash savings and usage of Kris points that were nearing expiry!